The USC-SCOR is engaged in three tasks: Task I - Clinical studies employing diagnostic methods developed by Task III to accomplish the following: a) A clinical description of patients with premature atherosclerosis and b) A clinical trial of weight loss-exercise on human lesion regression/progression. Task II - Studies of arterial wall metabolism with the aim of developing clinical diagnosis of susceptibility-durability of arterial wall. These studies involve bioenergetics, enzyme distribution, and ultrastructure of arteries. Task III - Development of new diagnostic methods for direct evaluation of human atherosclerosis. This is carried out by densitometer-computer analysis of angiographic images. The Task Teams are supported by four core laboratories: Core Angiographic-Diagnostic Laboratory; Core Lipid Laboratory; Core Vivaria; and Core Biostatistics Laboratory.